Modern technology has allowed the miniaturization of computers to the extent that portable computers may be used in the field to access, record, and process data.
A critical feature of any computer is the display system. For a portable computer the length of battery life is often critical and the use of a liquid crystal display (LCD) allows the use of a small battery to achieve reasonable battery life. However. LCDs have many drawbacks in that visibility is often limited in extreme lighting conditions and at certain viewing angles.
Additionally, the contrast of the liquid crystal is dependent upon its temperature. At extremely low temperatures the crystal tends to be opaque and at high temperatures it tends to be highly transparent Thus the voltage levels required to create a readable display must be adjusted to account for changes in temperature of the liquid crystal medium.
Thermistor circuits to compensate for heat generated internally by a computer are known. However, portable computers designed for field use will encounter a very wide range of operating temperatures from sub-freezing to summer conditions in vehicles and buildings. Compensation for such extremes is not possible with thermistor circuits.
Thus, there is a great need to improve the visibility of an LCD to provide portable computers having low weight and long battery life.